Basic Research On Micro-vibration Energy Harvester Using Diamagnetic Levitation

Micro-electromechanical system and devices have been used in the field ofmedical engineering, biological engineering, information and communication and soon. However, when these devices are used in the harsh environment or implantedinside the body of the measured system, the traditional power cannot meet the needof continuous supply of autonomous systems due to the frequent replacement forlimited energy storage. Power supply equipment hinders their further developmentand application, and energy harvesting technology attracts more and more attentionof the scholars, therefore.This paper proposed a kind of vibration energy harvester of diamagneticlevitation on the basis of domestic and foreign research status of electromagneticvibration energy harvester. Firstly, two structural schemes of diamagneticallylevitated vibration energy harvester were proposed according to the law ofelectromagnetic induction and diamagnetic levitation. Then the two schemes werecompared and a reasonable one was chosen, which consisted of lifting magnet,floating magnet, induction coil and pyrolytic graphite.Secondly, a method of eliminating deviation was proposed and validated whenthe magnetic and diamagnetic forces were calculated during the analysis process ofthe diamagnetically levitated vibration energy harvester with Ansoft Maxwell.According to the results of finite element analysis, a reasonable size of liftingmagnet, floating magnet, upper and lower pyrolytic graphite sheet was chosen. Thegravity, magnetic and diamagnetic forces of the floating magnet were analyzed andthe maximum suspended space was calculated. According to the research ofeccentric restoring force of floating magnet, the maximum tilt range of the systemwas obtained during installation and use.Then the pick-up system of the vibration energy harvester was equivalent to anapproximate linear system with the restoring force study of floating magnet. Usingthe forced vibration theory of linear systems, the vibration characteristics of energyharvester was analyzed. The nonlinear characteristics of the pick-up system were discussed and the differences with resonance condition were obtained when thepick-up system was equivalent to a linear system.Finally, the structural parameters of induction coil were optimized according tothe analysis of the magnetic field around floating magnet and the coil resistance. Thefinite element model of floating magnet and induction coil was built using finiteelement software Ansoft Maxwell, the induced voltage of induction coil wassimulated and the effects of parameters of induction coil, external vibrationfrequency and amplitude to the output voltage and power of vibration energyharvester were analyzed.